Time:
Before 2020/09/25, the company does not allow csdn, and the notes are written elsewhere. recently tidied up
1. Whether to start AppWidgetService
//第一个值调用PackageManager.hasSystemFeature
//第二个boolear值是false
if (mPackageManager.hasSystemFeature(PackageManager.FEATURE_APP_WIDGETS)
|| context.getResources().getBoolean(R.bool.config_enableAppWidgetService)) {
traceBeginAndSlog("StartAppWidgetService");
mSystemServiceManager.startService(APPWIDGET_SERVICE_CLASS);
traceEnd();
}
2. Condition judgment
PackageManager.hasSystemFeature
actually takes thePackageManagerService.hasSystemFeature
public boolean hasSystemFeature(String name, int version) {
// allow instant applications
synchronized (mAvailableFeatures) {
final FeatureInfo feat = mAvailableFeatures.get(name);
if (feat == null) {
return false;
} else {
return feat.version >= version;
}
}
}
3. Function switch source
The values in mAavailableFeatures come fromSystemConfig
SystemConfig systemConfig = SystemConfig.getInstance();
mAvailableFeatures = systemConfig.getAvailableFeatures();
4. Read the configuration in each directory in the construction method
SystemConfig() {
// Read configuration from system
readPermissions(Environment.buildPath(
Environment.getRootDirectory(), "etc", "sysconfig"), ALLOW_ALL);
// Read configuration from the old permissions dir
readPermissions(Environment.buildPath(
Environment.getRootDirectory(), "etc", "permissions"), ALLOW_ALL);
// Vendors are only allowed to customize these
int vendorPermissionFlag = ALLOW_LIBS | ALLOW_FEATURES | ALLOW_PRIVAPP_PERMISSIONS
| ALLOW_ASSOCIATIONS;
if (Build.VERSION.FIRST_SDK_INT <= Build.VERSION_CODES.O_MR1) {
// For backward compatibility
vendorPermissionFlag |= (ALLOW_PERMISSIONS | ALLOW_APP_CONFIGS);
}
readPermissions(Environment.buildPath(
Environment.getVendorDirectory(), "etc", "sysconfig"), vendorPermissionFlag);
readPermissions(Environment.buildPath(
Environment.getVendorDirectory(), "etc", "permissions"), vendorPermissionFlag);
// Allow ODM to customize system configs as much as Vendor, because /odm is another
// vendor partition other than /vendor.
int odmPermissionFlag = vendorPermissionFlag;
readPermissions(Environment.buildPath(
Environment.getOdmDirectory(), "etc", "sysconfig"), odmPermissionFlag);
readPermissions(Environment.buildPath(
Environment.getOdmDirectory(), "etc", "permissions"), odmPermissionFlag);
String skuProperty = SystemProperties.get(SKU_PROPERTY, "");
if (!skuProperty.isEmpty()) {
String skuDir = "sku_" + skuProperty;
readPermissions(Environment.buildPath(
Environment.getOdmDirectory(), "etc", "sysconfig", skuDir), odmPermissionFlag);
readPermissions(Environment.buildPath(
Environment.getOdmDirectory(), "etc", "permissions", skuDir),
odmPermissionFlag);
}
5. Finally read the handheld_core_hardware.xml of /vendor/etc/permissions
rom root path global search configuration
sprocomm@Srv50:~/sdb/MTK_Q/alps$ find -type f -name '*xml'|xargs grep --color=auto -rn 'name="android.software.app_widgets"'
./frameworks/native/data/etc/tablet_core_hardware.xml:43: <feature name="android.software.app_widgets" />
./frameworks/native/data/etc/handheld_core_hardware.xml:42: <feature name="android.software.app_widgets" />
./frameworks/native/data/etc/android.software.app_widgets.xml:18: <feature name="android.software.app_widgets" />